Electrical discharge device



April 30, 1935. R. RUDENBERG ETAL 1,999,597

ELECTRICAL DISCHARGE DEVICE Filed April 22, 1955 WIT E INVENTORS NESS S Pez'nfzoZd Rude/Mar 3? Max Szeenbe a BY V I ATTORNEY Patented Apr. 30, 1935 UNITED STATES ELECTRICAL DISCHARGE DEVICE Reinhold Rudenberg, Berlin-Grunewald, and Max Steenbeck, Berlin-Siemensstadt, Germany, assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsylvania Application April 22, 1933, Serial No. 667,486 In Germany April 25, 1932 8 Claims.

Our invention relates to electrical discharge devices and especially to the combination of such devices with a control circuit therefor.

An object of our invention is to provide a control circuit utilizing large current densities in the control of an electrical discharge device.

Another object of our invention is to provide a control circuit that shall momentarily charge the control electrode of an electrical discharge device.

Another object of our invention is to provide a control circuit for an electron discharge device utilizing heavy currents in which the grid is not unduly heated. 7

Other objects of our invention will be apparent through reading the following specification, taken in connection with the accompanying drawing, in which:

Figure 1 is a diagrammatic view of a preferred system incorporating my invention; and 7 Fig.2 is a diagrammatic view of a modification of the system disclosed in Fig. 1.-

The electrical discharge device [0 in Fig. 1 may begof the usual vacuum type, including the anode l i, grid I2, and cathode l3. The cathode l3 may be an incandescent cathode, although other types of cathodes may be used, such as a mercury cathode or a glow cathode.

When a discharge has been initiated between the anode H and the cathode I3, it is possible to extinguish it by causing a condenser to send a current impulse momentarily in an opposite direction through the tube. This method has the drawback that it effects the main current circuit, and also that it requires relatively large extinguishing capacities.

The use of a grid to extinguish the discharge, as taught by the prior art, has the drawback that it is operable at relatively small current densities only and fails at larger current densities. The failure of the grid in the devices of the prior art with large current densities is caused by the fact that the blocking action of a negatively charged grid located in the path of the discharge is partially counteracted or neutralized by layers of positive ions which collect on or around the grid wires. The grid'wires act only in a very small and definitely limiting area in a manner to block the discharge. The greater part of the meshes of the grid, however, remain penetrable. If a very high negative grid voltage is connected to the grid, the positive ion stream will cause the highly charged grid to glow, whereby it will emit electrons and lose completely its blocking action.

According to our invention, the discharge is extinguished with the help of the grid 12 10- cated in the path of the discharge by momentarily charging the grid to a very high negative potential, so that the thickness of the layer of the positive discharge clouds surrounding the grid will be larger than the width of the openings in the grid. The instantaneous extinguishment of the discharge is thereby eifected. The length of time of the impulse serving to extinguish the discharge is less than the time in which the grid can be heated to a temperature, wholly or locally, by the grid current-to cause emission of the electrons mentioned above.

We prefer to have the control grid I2 made of meshes as small as possible without having the grid heated to too great a temperature by the discharge. Grids having a very small mesh increase the resistance of the discharge path to a large degree, and, therefore, result in the development of a large amount of heat in the neighborhood of the grid. It willprobably be preferable to select a dimension of one-half to one millimeter'for the meshes. The grid is so arranged that the discharge from the cathode can reach the anode only by passing through the grid. This, of course, may be accomplished by extending the grid completely across the tube Ill, or by substantially completely surrounding the active surface of either the anode II or cathode I3 with the grid.

The control circuit whereby the grid is momentarily charged may be one of several forms, but a preferred form is disclosed in Fig. 1. A supersaturated iron core l4, and its associated circuits, is utilized to obtain a very sharp voltage peak. The magnetism of the core is provided by the coils l5 supplied by the alternator I6. The magnetic fiux through the core is controlled or regulated by the coil it around the core and connected to the resistance I1 and current supply l8. core, which isin shunt with the condenser 20, provides the means of supplying the high-voltage peak to the grid 12.

It is desired that the charging of the current be effected very rapidly, such as on the order of 10 to 10' seconds. The momentary charg-' ing of the grid is accomplished by placing the spark gap apparatus 2| in series between the grid l2 and the iron core and its associated cir- The coil 19 also around the I the ordenoflOi seconds. 1

blocking action. The passage of current through illustrated. The grid 25 will preventjreigni-tionof the discharge following the ex'tinguishment of the discharge, where the grid 12 may have a positive oscillatory charge gforsa time.

While we have illustrated the embodimentsof our invention, it will be apparent to those skilled in the art that various changes and modifica tions -may be made therein without, departing iromthe-spirit and scope of our-invention, and it .is desired, therefore, that only such limitationsshallbe imposed thereonas ,arei-ndicated inthe-cprionartor are setwforth in the appended claims.

We claim as ourinvention: l1. :In combinationan electrical discharge devicehaving ananode, cathode and control electrode, anda controlcircuit for said device, said control circuit qhavingymeans f,or momentarily charging .saidcontrolelectrode for a periodzin :2. .-In combinatiorran electrical discharge device-havingan ,anode,,cathode and two grids, and .a control. circuit for said device, said contr,ol

circuit having ,meansior momentarily charging :p-neof said grids to a high negative poten- :tial andmeans for vchar ng the oth r gri a .ailowznegative potential.

3.,,In combination,.an electrical discharge de- -.vicejha-ving an anode, cathode and control elecvtrode,eanda control circuit for said device includingasource of; potential and a spark gap a' paratusior momentarily charging said con,-

.trol electrode.

4. In combination, an electrical discharge device having an anode, cathode and control electrode, and a control circuit for said device in cluding a source of potential and a spark gap apparatus and a supersaturated iron core circuit for momentarily charging said-control electrode toa high negative potential.

5. In combination, an electrical discharge de- -vice having an anode, cathode and twogrids, .and a control circuit for said device, said control circuit including a source of potential and a spark gap apparatus for momentarily charging one of said'grids and means for charging the other of said grids at a low negative potential.

6. In combination, an electrical discharge device having an anode, cathode and two grids, and a control circuit for said device, said control circuit including a. source of potential and a spark gap apparatus and a supersaturated iron core circuit for -momentarily charging one of said grids to a high negative potential and'means for charging the other of said grids at a low negative potential.

--7. The method-of-extinguishing dischargesdn vacuum containers by meansof a grid located in the dischargepath and which iswrappedup by positive space discharge clouds which comprises charging said grid with a high negative potential for only such a shortperiodthatthe grid is not heated to a temperature oapableof causing an electron emission in the positive space discharge clouds which form-around said rid.

8. Incombination, an electrical discharge device having an anodejcathode and-control- 'electrode, and a control circuit for said device 'includinga 'source of potential and a breakdown apparatus and a supersaturatediron core circuit for momentarily charging said control-electrode to a high negative potential.

-REINHOLD 'RUDENBERG.

MAX STEENBECK. 7 

